Re:Homemade GPS Receiver (2013)
by blattimwind on Tuesday June 26, 2018 @10:45AM
(#17400950)
> Some differential lines (e.g. RS-485, popular in industrial automation) use current signalling thus requiring two wires per signal.
Virtually all high-speed digital communication uses differential signalling.
Agree on that, but all high speed interconnects I know use voltage signalling.
Re:Homemade GPS Receiver (2013)
by blattimwind on Wednesday June 27, 2018 @03:45AM
(#17406436)
That's orthogonal to differential or single ended, but typically the transmit side uses some form of current steering; it just goes well with it.
E.g. PCIe transmitters are HSCL, which is a form of current steering that gives the receiver exactly the voltages it needs to see at nominal currents and termination values.
It gets even stranger: https://en.wikipedia.org/wiki/Star_quad_cable
Third wire does not collect interference in a balanced line. Instead, voltage signalling balanced line uses one ground and two signal lines of opposite polarity and input is difference between these two signal lines. Induced interference is more or less the same on both signal lines, therefore cancels out. At a quick glance this article [1] seems to explain this without delving into electronics. Some differential lines (e.g. RS-485, popular in industrial automation) use current signalling thus requiring two wires per signal.
[0]: http://www.cliffuk.co.uk/products/combijacks/combijacks.jpg [1]: http://www.aviom.com/blog/balanced-vs-unbalanced/